Physical Pharmacy Flashcards
Physical pharmacy
Quantitative and theoretical aspects
Three fundamental dimensions
Length
Mass
Time
Force
Directly proportional to the mass when acceleration is constant and vice versa
f= m*a
Dynes
Pressure
Force per unite area
dyne/cm^2 = atm = mercury
density * gravity * height = pressure
Energy
Property of a bdoy that gives it the capacity to work
1 erg = 1 dyne * 1 cm
1 joule = 1*10^7 erg
Thermal energy
Amount of heat necessary to raise the temperature of 1 gram of water from 15 to 15 celsius
Calorie = 4.184 joules
Intermolecular forces
Forces that keep molecules in aggregates in gases, liquids and solids
Repulsive forces
Molecules are brought close enough together that the outer charge clouds of the molecules touch
Attractive forcues
Bring molecules together
Cohesion: like molecules
Adhesion: unlike molecule
Van der Waals Forces types
Keesom (dipole-dipole)
Debey (dipole-induced dipole)
London (induced dipole-induced dipole)
States of matter
Gases
Liquids
Crystalline solids
Sublimation
Solids with high vapor pressure may pass directly from the solid to the gaseous state
Deposition
Recondensation to the solid state
Mesophase
Between liquid and crystalline states
Gaseous state
Vigorous randome motion and frequently collide
Critical temperature
Very high temperature, a gas cannot be liquefied regardless the pressure applied and the temperature above which a gas cannot exist in liquid state
Critical Pressure
Pressure required to liquefy a gas at its critical temperature
Aerosols
Drug is dissolved in a propellant (liquid under pressure but gas in air)
Polymorphism
Exist in more than one crystalline form
Contain solvents: solvates or pseudopolymorphs
Enatiotropic
When the change from one form to another ir reversible
Monotropic
When change from one to another is one directional
Amorphous solids: Supercooled liquids
Molecules in amorphous solid are arranged in a random manner
Do not have a definite melting point
Isotropic (similar properties at different directions)
Anisotropic (different characteristics in different directions)
